What happens at the underlying economic level (the way the economy is run, e.g. who has the economic power) will determine what happens at the cultural level, including religion, rest and recreation, science, art, romantic life, family life, the government/state (so both other "levels" from Hegel can be described as really two examples of the superstructure "level" if we're thinking about it divided up like this. Both metaphors of "levels" are just metaphors, after all.), etc..

This isn't just a matter of the rulers dictating the ideas, or censoring other ideas, though of course that can happen too, and frequently does.

It's also a matter of much more subtle and complex, though immensely powerful, influences.

For example, bureaucrats and corporate businesspeople whose careers depend on keeping the status quo authorities happy (government authorities and/or private-sector authorities, any authorities who are powerful) will tend to interpret and promulgate data in the way that is most charitable to those authorities.

This is the main idea behind the famous line: "History is written by the winners."

There's a similar line around these days about somebody being able to deny something obviously true if his paycheck requires him to do that.

Note that in these cases, the people affected may be consciously, deliberately lying, or they may be lying to themselves as well, or so much "in denial" about things for so long that it's not so much self-deception as just living with blinkers carefully kept on, carefully not asking questions, carefully keeping certain topics off-limits. These last two typically occur in cases of "groupthink," such as the infamous decision to start the Bay of Pigs attack, the catastrophic decision to allow the Challenger to be launched, the controversial decision of Oppenheimer and his colleagues to continue with the Manhattan Project after Germany's surrender (or at least their lack of a decision to stop work), and countless others.

(Noam Chomsky's famous media analyses frequently reveal what seems to be this kind of influence, as well as apparent cases of open distortion and deceit.)

(This is also one of the strongest reasons for defending academic freedom from state (and corporate) control, so that professors, e.g. science and history professors, don't have to fend off that kind of pressure, and can report their information with the greatest objectivity and precision of which they're capable.)

(Note that in this country, the apparently "commonsense" ideology leads us easily to suspect government control, but not corporate control. That's just an ideological distortion, since any power can be a threat, public- or private-sector.)

More subtly and perhaps even more dangerously, though, there can also be ideological pressures that are completely out of perception, and that can thus influence even someone of great integrity, if he or she isn't aware of them.

Sound strange? Think of it like this:

Of all the ideas that get played with and juggled around, the ideas that happen to be in synch with the current power structure (think: economy) are going to seem most commonsensible. They'll look familiar. They'll resonate. They'll have the ring of truth. Why? Not because they actually have the ring of truth, but because they fit the workday, shopping-day, everyday (economic) environment that we've made for ourselves. So of course these are the ideas that we'll most readily believe.

"structure" or "substructure": The underlying economic system, including the "material life" such as geography, natural resources, population density, and the "mode of production," such as tribal, slave-holding, feudal, capitalistic.

Example:

These days, in this country, we all (I think and hope) regard slavery as abominable, even "unnatural." Our economy no longer relies on it. (Indeed, our economy now needs as many consumers as possible, to be markets. Slaves, who wouldn't be able to afford to be consumers, would hurt the current economy). Marx would say that our ideology has thus adapted to this far more acceptable situation. (Many 19th-Europeans such as Marx were appalled by pre-Civil War U.S. slavery.)

But many societies before now regarded slavery as entirely "natural," when slavery was required to maximize wealth for the wealth-owners. (Of course, whether this trade-off was worth it is another question entirely.)

Incidentally, some cynical historians cite this as one possible reason for the northern states' declaring war on the confederacy in the U.S. Civil War: The north couldn't compete economically with the incredibly cheap slave-labor in the south. Marx would probably believe this reason, rather than the inherent goodness and ideals of the northerners. I hope Marx would be wrong here, but don't know enough to hold an opinion on this matter myself.

Fortunately, we can use reason to look critically at the arguments for and against slavery, to transcend the unreliable feeling of familiarity or unfamiliarity that ideological distortions can hide behind. And then we find that even Golden-Age ancient Greek Aristotle, living in a culture in which slavery was so accepted that it was just taken for granted, and limited by his identification with the economic and cultural elite, acknowledged slavery as a great source of suffering, and hypothesized that a much better society would be possible if automatons were ever invented that could perform certain simple tasks. (How's that for impressive predictions? It is possible to escape many ideological distortions, with enough integrity and imagination!)

2. One example: Capitalism

Marx is opposed to the capitalist economic system for many reasons. Most directly, he's opposed to the economic injustice that he thinks it perpetrates. Even if workers were not very badly treated and paid mere subsistence wages (and most were, in his lifetime and beyond), capitalism is inherently unjust, he believes, in that it is driven by an investor or investors (i.e. those providing the "capital") collecting the profit, not those who are doing the actual work, creating the extra value. And in economic terms, he's pretty indubitably correct in his analysis here, however we assess the situation ethically.

After all, where does profit come from? From "underpaid labor": The difference between the low exchange-value of labor, i.e. wage or salary, and the higher use-value of that labor, i.e. what the employee produces. (For more, see "Basic Economic Terms from Adam Smith and Marx" on my web page.)

(Now, a post-Marxian development: workers now, though, are also consumers. Faced with overproduction, i.e. too few consumers who could afford to be a "market" for their products, manufacturers began paying their workers better. This gave the manufacturers a larger market, and simultaneously placated the workers enough to lessen the strikes and political agitation occurring in the U.S. and Europe in the last half of the 19th century and the beginning of the 20th. The "company store" became much brighter and more appealing. In fact, now many people get their very sense of who they are from their consumer choices. Nowadays, employers need not only good, unquestioning, obedient workers, but also good, unquestioning, obedient, but demanding consumers.)

But Marx isn't just upset about the economic injustice of capitalists/investors getting value that was created by the workers. Even more, he's angry that under capitalism people are being inculcated with falsehoods, "mystified," in a really neurotic, un-free, way. Here are a few examples of distorting, "mystifying," ideological beliefs:

a.
As we've seen early, Hegel describes three separate societal levels of family, civil society, state, but Marx says that civil society is in fact controlling the state.

b. "Freedom" and "Equality" are used in equivocal (ambiguous) ways. As Marx puts it with his typical sarcasm:This sphere [of buying and selling labor, i.e. employment] . . . is a very Eden of the innate rights of man. There alone rule Freedom, Equality, Property, and Bentham.Freedom because both buyer and seller of a commodity, say of labout-power, are constrained only by their own free will. [Despite the fact that hunger also constrains, that a poorlyl educated, unskilled worker has limited options, and that the capitalist market itself will force the employer to cut wages as low as possible.]Equality, because each enters into relation with the other, as with a simple owner of commoditeis, and they exchange equivalent for equivalent. [Despite the economic power that the employer has over the employee, and the fact that the equivalent offered for his labor is equivalent only in "exchange-value," i.e. what it'll get on the market, and not in "use-value," what can be done with it, and that the difference, "surplus value," will be kept by the employer as profit.]Property, because each disposes only of what is his own. [Despite the fact that the wages traded by the employer are, though legally his own, still derived from the unpaid labor of previous workers.]And Bentham, because each looks only to himself. (From "The Buying and Selling of Labour-Power," from Capital, vol. I, reprinted in The Marx-Engels Reader, ed. Robert C. Tucker, p. 343.)

c.
Here's a classic example of ideology from sarcastic Anatole France:"The law in its majesty equally forbids rich and poor from sleeping under the bridges!"

d. The Protestant work ethic as described by Max Weber:Calvinism, with its doctrine of predestination and the very low value of corrupt humanity, redirects people's attention away from helping each other and towards worrying about whether one is saved, or "elect," oneself. The worrying Calvinist seeks evidence that God approves of him: Is he successful in his work? But even if he becomes very wealthy, it befits him as a corrupt human not to enjoy that wealth. Instead, there's a kind of updated asceticism, now adopted by the miser, who begins to see acquiring wealth as an end in itself rather than a means to security and pleasure. (For more, see "The Calvinist Work Ethic and Consumerism" on my webpage.)

Even worse than this mystification, though, is what Marx calls the alienation that capitalism imposes on us, with its concomitant devaluing of human life and creativity and potential and individuality. In general, with capitalism, we are being controlled by our own human creation: the system of economics we use. Some of us are still being physically destroyed by it, e.g. by dangerous workplaces and by industrial pollution, and many of us are being psychologically, "spiritually," destroyed by it, as we are treated as though we were merely a unit of "human resources," or merely a unit of consumer capacity.

Something that is very ironic: We are held captive and alienated by our own human creation. We treat the economy (and the discipline of economics, too) as if it were an eternal and independent power, a natural law, that we must obey, even to the point of resigning ourselves to unnecessary deaths (Marx's examples of unnecessary deaths would be from worker mistreatment, unemployment and below-subsistence wages and resulting starvation. Current examples: from inadequate health care for the uninsurable, from toxic waste, from environmental instability caused by global warming) rather than challenge what is currently regarded as "economic growth." (For more, see "A Few Economic Myths" on my webpage.)

But the economy and our economic preconceptions are all human products – in fact, the current economy is a very recent human product, and there have been many alternatives in human history. We can take charge of this creation and change it so that it benefits the human race, rather than letting it run us to the point of injuring most of us.

And, if the economic sub-structure determines our cultural superstructure, we can use this knowledge deliberately to build an economy that will allow the most beneficial culture, with more human freedom, more individuality, that encourages each of us to develop our potential. (Marx share's Mill's and others' faith in humanity's progress. At one point he actually refers to his contemporary era, the 19th century, as "prehistory," since that's how he thought future, fortunate, people would regard it!)

Thus, classical Marxists think that racism and sexism are underpinned by economic oppression. Racism and sexism would be, to put it simply, symptoms, dehumanizing attitudes that would excuse keeping them from obtaining equitable economic power – the real power. For classical Marxists, the only final end to racism and sexism will come by changing the economic substructure to redress this injustice. After that, the discriminating attitudes would automatically fall away, since they'd be obsolete. And at that point, the dehumanizing alienation that affects everyone under capitalism would also evaporate.

Some historical examples seem to support this view: Astonishingly, Castro's Cuba has almost entirely eliminated a particularly extreme racism in a few decades by focusing on radical economic change, whatever Castro's other failings have been. On the other hand, this may have been an unusually responsive case. In Batista-era (pre-Castro) Cuba, there were few middle-class people, only a handful of extremely wealthy and a majority stuck in grinding poverty, forced prostitution, etc.. When the revolution occurred, the corrupt regime and its sympathizers simply fled the island, so that the remaining Cubans had a high level of consensus, of shared experiences and goals, that helped to transcend racial divides.

Other theorists, including many people heavily influenced by Marx, acknowledge that economic oppression certainly influences racism and sexism, but insist that the culture (including attitudes about race and gender) can also influence the economy, not just vice versa. It's a two-way influence, many hold. According to yet others, racist and sexist attitudes may even be the cause of economic oppression of women and oppressed ethnic groups. For instance, Gerda Lerner argues that women's oppression is the earliest and most basic oppression, and led to economic oppression in general, e.g. to the practice of slavery. Marx would disagree, claiming that economic oppression is the basic problem, and that sexism is a result of this, not the cause.